Plant for continuously refining pig iron

ABSTRACT

The invention relates to a plant for continuously refining pig iron comprising a vessel for storing and keeping warm pig iron and a closed spray-refining vessel in which a gaseous refining agent is blown onto a falling pig iron stream and an about horizontal spraying cone is formed, in which the improvement resides in that the vessel for storing and keeping warm the pig iron is provided with at least one electromagnetic conveying groove starting from its floor and ascending slantingly, its upper end ending into a supply funnel of the spray refining vessel. With this arrangement the advantage is gained that a uniform amount of liquid pig iron may continuously be fed into a spray refining vessel so that the amounts of refining gas and additions need not be changed.

United States Patent Hager 1 Sept. 19, 1972 [54] PLANT FOR CONTINUOUSLY3,272,618 9/1966 Miller ..75/60 REFINING PIG IRON 3,558,121 1/1971 Lenne..266/34 V [72] Inventor: Mot Hag", Linz, Austria 3,610,600 10/1971Schnake ..266/34 V [73] Assignee: Vereinigte Osterreich-ische Eisen-Primary Examiner-Gerald A. Dost und Stahlwerke Aktiengesellschaft,Attorney-Brumbaugh, Graves, Donohue & Raymond Linz, Austria 221 Filed:Feb. 11, 1971 l ABSIRAI e invention re ates to a p ant or continuouslyrefin- [zll Appl' 1l6087 ing pigiron comprising a vessel for storing andkeeping warm pig iron and a closed spray-refining vessel in [30] ForeignApplication Priority Data which a gaseous reifiningbzgenlt is blozvalnonto a falling pig iron stream an an a at orizon spraying cone Feb. 20,1970 Austria ..1556 is formed, in which the improvement resides in thatthe vessel for storing and keeping warm the pig iron is [52] US. Cl...266/l3, 755226554201 provided with at least one electromagneticconveying 51 I L Cl C2 7100 groove starting from its floor and ascendingslantingly, I 'g 59 60 its upper end end ng into a supply funnel of thespray I 1 o 266/34R 5 2 refining vessel. With this arrangement theadvantage is gained that a uniform amount of liquid pig iron may edcontinuously be fed into a spray refining vessel so that [56] ReferencesIt the amounts of refining gas and additions need not be UNITED STATESPATENTS changed- 949,474 2/1910 Hawkins et al. ..75/52 3 Claims, 2Drawing Figures P TENTEDsEP 19 I972 3592290 FIG.I

INVENTOR A L 015 HA GEP SZ L, (IQ-11mm, BY Mm t W his ATTORNEYS PLANTFOR CONTINUOUSLY REFINING PIG IRON The invention relates to a plant forcontinuously refining pig iron comprising a vessel for storing andkeeping warm pig iron and a closed spray-refining vessel in which agaseous refining agent is blown onto a falling pig iron stream and asubstantially horizontal spraying cone is formed. The falling pig ironstream is sprayed by the refining gas, e.g., pure oxygen oroxygen-enriched compressed air, and distributed into a plurality ofdroplets. The refined pig iron, or the steel, respectively, is collectedon the floor of the vessel under formation of a sump and continuouslytapped. The steel may run off into ladles and may be cast e.g., in acontinuous casting plant.

In spray refining, slag forming agents, e.g., lime, fluorspar, bauxiteand the like and other additions, such as ore or lime stone, are addedeither throughan input funnel for the supply of the pig iron to therefining vessel or through special openings in the cover of the refiningvessel and get into the sphere of action of the blowing jet or of thespraying cone, respectively.

All solid additions and the refining gas must be added to the refiningvessel in exactly the amount which corresponds to the amount of suppliedpig iron. Therefore it is suitable to keep constant the pig iron amountwhich is supplied through the input funnel into the refining vessel pertime unit. As soon as variations occur in the amount of pig ironsupplied per time unit, the amounts of refining gas and slag formerssupplied have to be adapted to the changed amount of pig iron;

. with the helpof which a constant amount of liquid pig thus regulationproblems occur which are difficult to be mastered and have remainedunsolved so far; it has not been possible so far to conduct the sprayrefining process exact and to produce a refined product of the desiredfinal analysis and temperature. So far, the pig iron was supplied intothe refining vessel by use of stopper ladles. in doing so, the ladleswere set upon electronic scales, and the stopper of the casting ladlewas operated pneumatically, for example. The change of the weightindicator of the scales was used asa measure for adjusting the stopperregulating the amount of outflow of the pig iron. Since the amount ofpig iron flowing out from the floor opening of the stopper ladle pertime unit greatly decreases with sinking melt level in the ladle, theposition of the stopper has to be changed continuously in order to keepconstant the amount of pig iron supplied to the refining vessel per timeunit. it is difficult to carry out an automatic regulation of the pigiron supply because owing to the necessary exchange of ladles theoperation is interrupted. It is rather time consuming to adjust thedesired operation conditions after each ladle exchange; considerablevariations occur in the chemical composition and in the temperature ofthe refined product produced during this time period so that, so far, ithas not been possible to cast steel produced according to the sprayrefining process to blocks suitable as pre-product for the rolling mill.The steel has to be further treated for correcting its analysis andtapping temperature. This rather bothersome working method is not onlyexpensive but it is also the main reason that so far it has not beenpossible to realize an absolutely continuous spray refining operation.

The invention is aimed at avoiding these disadvantages and difficultiesand at creating an appliance iron may continuously be supplied to aspray refining vessel so that the amounts of refining gas and additionswhich have to be supplied to the refining vessel need not be changed.

In a plant for continuously refining pig iron of the type defined in theintroductory part, these aims of the invention are achieved in that thevessel for storing and keeping warm the pig iron is provided with atleast one electromagnetic conveying groove starting from its floor andascending slantingly and in that the upper end of this conveying grooveends into a supply funnel of the spray refining vessel.

Preferably the upper end of the conveying groove ends in the inner faceof the supply funnel and terminates flush with this face.

The vessel for storing and keeping warm the pig iron may be providedwith two electromagnetic conveying grooves, the grooves being connectedwith a spray refining vessel each.

ln order that the invention may be more fully understood an embodimentthereof shall now be explained with reference to the accompanyingdrawing.

FIG. 1 is a top view of a plant in a schematical representation and FIG.2 is a sectional view along the line 11-" of FIG. 1 on an enlargedscale. v

In FIG. 1 numerals l and Z'denote the two furnaces of a blast furnaceplant and numeral 3 denotes their blast preheaters. The liquid pig ironmay run through grooves 4, 5 into a storing vessel 6. The storing vessel6 is situated on a lower level than the furnaces 1,2. By heating means 7the pig iron contained in the storing vessel is kept warm. 8 and 9 aretwo electromagnetic conveying grooves for transporting the liquid pigiron from the storing vessel 6 into supply funnels 10 of spray refiningvessels 11, 12. The conveying grooves are inductive conveying means withtravelling electromagnetic fields. By means of a multi-phase winding 40connected to a conventional multi-phase power source (not shown), aprogressing magnetic field is built up, just as is the case with anormal induction motor; the iron melt follows this field in thedirection of its progress. The conveyed throughput amount per time unitdepends in a given arrangement only on the voltage applied at thewinding or the inductor, respectively, and is not influenced by thechanging bath level in the storing vessel. This great advantage of theelectromagnetic conveying groove makes the dosing or control processindependent from a precise measurement of the bath level in the storingvessel 6 or from a weight determination of the melt present in thestoring vessel. The conveying amounts which are adjustable to be exactlyreproduced are obtained exclusively by influencing electrical factors.The pig iron may be drawn from the storing vessel 6 without slag andconveyed slantingly in upward direction into the supply funnel 10. Therefined pig iron or the steel, respectively, is continuously tapped intoladles l3 and the slag runs off at the same time into slag buckets l4.Numerals l5 and 16 denote rails on which railbound vehicles not shown inthe drawing transport the casting ladles l3 and the slag buckets 14 toand fro. While the ladles are exchanged, the tap is closed for a shortperiod by closing means 17 designed in a known manner; the closing means17 is arranged to be rotatable.

FIG. 2 illustrates details of the arrangement of the conveying groove inrelation to the spray refining plant. The storage vessel 6 collects thepig iron 18 running in via the groove 4, and the slag 19. Theelectromagnetic conveying groove 8, which is arranged to be slanting inupward direction, leads from the floor of the storing vessel to theinlet opening in the side wall of the supply funnel 10. When the end ofthe supply groove 8 terminates flush with the side wall of the funnel 10a broad pig iron stream 18 runs through the bottom opening of the funnel10. The longitudinal axis of the slit-shaped bottom opening is arrangedvertically in relation to the longitudinal jet by means of which the pigiron stream 18' is atomized and refined under formation of a sprayingcone 22. 23 and 24 are means for adding slag forming agents into theinlet funnel 10. Through a further opening 25 in the vault of therefining vessel 12 small pieces of scrap may be added as cooling agent.On the floor of the refining vessel 12 the steel 26 and the slag 27 arecollected; they may continuously run off via tapping holes 28, 29. Thesteel tapping 28 leads from the fioor of the refining vessel slantinglyin upward direction so that a sump may be formed in the refining vessel12 and the complete reaction of the slag with the metal is facilitated.Numeral 30 denotes a tapping hole for emptying the refining vessel; thehole remains closed while operation is in progress. Also the storagevessel 6 is provided with a tapping hole 32 for voiding which islikewise closed during operation.-

The pig iron may also be conveyed to the storage vessel 6 by employingcustomary pig iron ladles. Obviously the storage vessel may be movableand may be designed in the manner of known torpedo-type mixers. Then, atransportation of liquid pig iron over wide distances is possible.

- The uniform conveyance of the liquid pig iron from the storing vesselin connection with the formation of a broad pig iron stream falling intothe refining vessel yields great operational advantages because theblowing jet may uniformly atomize the pig iron and the supplied amountof oxygen is optimally utilized.

What l claim is:

l. A plant for continuously refining pig iron comprising a vessel forstoring and keeping warm pig iron, at least one closed spray-refiningvessel in which a gaseous refining agent is blown onto a falling pigiron stream to atomize it under formation of a substantially horizontalspraying cone, and conveying means for transferring said pig ironbetween said vessels, said conveying means comprising at least oneelectromagnetic conveying groove having a lower end communicating withsaid vessel for storing and keeping warm pig iron at substantially floorlevel thereof, said groove ascending slantingly and ending with itsupper end into a supply funnel of said spray refining vessel.

2. The plant set forth in claim 1, wherein the upper end of theconveying groove ends in an inner face of the supply funnel andterminates flush with this face.

3. The plant set forth in claim 1, wherein the vessel for storing andkeeping warm pig iron is provided with two electromagnetic conveyinggrooves, each of the grooves being connected with a separate sprayrefining vessel.

1. A plant for continuously refining pig iron comprising a vessel forstoring and keeping warm pig iron, at least one closed spray-refiningvessel in which a gaseous refining agent is blown onto a falling pigiron stream to atomize it under formation of a substantially horizontalspraying cone, and conveying means for transferring said pig ironbetween said vessels, said conveying means comprising at least oneelectromagnetic conveying groove having a lower end communicating withsaid vessel for storing and keeping warm pig iron at substantially floorlevel thereof, said groove ascending slantingly and ending with itsupper end into a supply funnel of said spray refining vessel.
 2. Theplant set forth in claim 1, wherein the upper end of the conveyinggroove ends in an inner face of the supply funnel and terminates flushwith this face.
 3. The plant set forth in claim 1, wherein the vesselfor storing and keeping warm pig iron is provided with twoelectromagnetic conveying grooves, each of the grooves being connectedwith a separate spray refining vessel.